Dimensionality() indicates the level of subtotals in pivot tables. For example, if you have a pivot table with dimensions A, B, C and D,
the expressions will have a dimensionality of 5
subtotals for D will have a dimensionality of 4
subtotals for C will have a dimensionality of 3
subtotals for B will have a dimensionality of 2
subtotals for A will have a dimensionality of 1
the grand total will have a dimensionality of 0
This allows you to tailor the expression to the return the correct value for the totals if you need something other than simple subtotals.
That said - this is fairly advanced concept. Try to understand the basics before diving into advanced aggregations and complex expressions.
Hope that helps
It would be a gr8 help for me if you can give example along, we are having group sessions where in which I was assigned with this topic ,which i need to research and present, so kindly help me out in briefing the same with example and the key purpose of this function.
Thanks for the helpful answer once again !!